How to make a BBR rocket masonry heater firebox frame out of an old wood stove
Today I started modifying a Vogelzang Frontiersman wood stove I found on Craigslist for $45. I simply used a Harbor Freight 7” angle grinder ($45 with coupon) and Metabo cutting disks to modify it.
First I removed all the firebricks lining the wood stove and cut out the top, then the angle iron on the insides of the left, right and rear wood stove walls that previously held the firebricks in place.
I’m left with an empty 21” wide x 17.5” deep by 15” tall rectangular steel box that I can use to hold my 6” or 8” rocket core. (I’ll add a photo from a recent 8” masonry rocket heater build that utilized one of these wood stoves, but the core was in a traditional front to rear, left sidewinder orientation. I had to add door glass to the firebox door.)
This took less than an hour of light work yesterday afternoon. In this build, I’m going to use a 6” BBR core oriented from left to right, with the firebox door being part of the right hand wall of the firebox. Port will be in the ceiling of the firebox on the far right, with a double shoebox riser directly above the firebox.
A 24”x24”x14” deep square 14g steel box will sit directly over the wood stove with double shoe box firebox and riser, and that will sit between 2 masonry benches on my family room fireplace hearth.
But I just wanted to show how easy and cheap it can be to use old plate steel wood stoves like the Frontiersman to solve the issue of how to “build and mount” a firebox door with glass window.
I’m using one of my 6” shippable cores (with minor modifications) to build this firebox and double shoebox riser configuration, and I’ll add pictures as that takes shape. The primary air holes already in the firebox door will be modified for primary air. The holes under the door in the wood stove frame will be modified and used to introduce the secondary air through the recess in the 1” ceramic fiber board under the firebrick split floor of the firebox. (The two current air holes currently seen in the rear wall of the wood stove will be sealed off by the left side wall of the firebox.)
Just to be clear, you can’t use just any old wood stove for these purposes. It needs to be a lighter gauge plate steel body (not cast iron) for ease of modification while maintaining structural integrity, and the size and shape of both the firebox and door have to both be easily modified and incorporated into the rocket heater build. Plus if it was mass produced for a long time at an inexpensive price point when new, it’s often cheaper on the used market. Doors with glass are a bonus; double doors or doors that are too wide or tall or have an odd mechanism for closing or latching should be avoided.
Frankly, I’ve searched literally thousands of Craigslist ads from several states here in northeastern USA, and the only unit I’ve found so far that meets all these criteria is the Vogelzang Frontiersman. I suspect that an Englander NC13 ( maybe the NC30) would also work, but I haven’t seen one in person yet. I’m sure there are others but I haven’t found them yet.
So far I’ve found three of these particular stoves on Craigslist. I picked up the first two for $45 each, and the third for $150 last week. But it came with 10’ of class A stainless steel chimney including a complete through the roof assembly, and I sold that tonight on Craigslist for $125. So for a net investment of $115 I’ve gotten 3 full wood stoves to modify - $38 each.
Next: Finish the firebox, the double shoe box riser (DSR), build the benches using reclaimed old 18”x9”x4.5” firebrick and 2’x2’ cement sidewalk pavers, figure out how to integrate this Conservo Toledo Cooker as a white oven, cap the rocket primary bell with a 14g square 24”x24”x 14” sheet metal box maintaining enough breathing space between the DSR and the cap, and apply a blast gate as a bypass damper on the bottom rear of the 24”x24” metal box cap...
Over here in the UK I've used the modified body and door of a Charnwood Country 4 stove in my 5" BB Mass heater. I had to cut the back off it and add a 'new' section to get the recommended firebox depth (as per Peters specs).
It works very well.
The firebox is now complete, along with the Double Shoebox Riser (DSR) on top, and the secondary air tube and flange are now mounted. The holes in the wood stove frame under the door were widened to provide increased secondary air area.
I have a 14 gauge sheet metal square box that’s 24”x24”x14” tall that’s going to sit above this. It has a 6” round flue collar on the bottom rear of the box that I’m going to use as a bypass with a blast gate. Since the wood stove is only 17” deep, there will be a 7”x24” space at the rear for the exhaust to pass into two blind masonry benches. One of those benches will contain this Conservo Toledo Cooker as a white oven. The whole assembly will sit on a 10” hearth in front of a fireplace so a chimney won’t be very difficult.
Test fit, temporary while I make measurements for the masonry benches. Hearth is 96” wide, and now 27” deep since I extended it. The wood stove is 24” wide, 17” tall. The square metal box on top of it is 24”x24”x14” tall. Benches will be blind ended and 24”x24”, with 2’ bench to the right of the rocket and 4’ to the left. The metal box on top will have a 4”x6” mica glass viewport into the DSR above the firebox, with a view into the area above the port.
Bravo!! I love it when recycled items fit so well in a project.
Have you noticed any sagging issues with the fiber board on top of the burn box? The reason I am asking is because I am building my burn chamber and riser above my batch box and want to cover the top of my fire bricks in the box with fiber board like you have.
I noticed some fiber board has clay added to help prevent sagging. What grade fiber board are you using?
Satamax Antone wrote:So Brian, any update on this one?
Unfortunately I’ve moved to New England and I’m not currently involved in any rocket heater builds. But “Uncle Mud” Chris McClellen actually installed this particular build in his home.
He sent me an update about the installation in early December:
“Your double shoebox is a lovely addition to our home. It does smoke when you are feeding it and not as clean/stingy as a regular rocket but REALLY great to watch the flames on and a nice long burn with the flooring cutoffs we use.”
If he’s around the Permies forum, maybe he can stop in and comment further, but I’m not sure how to “ping” him to this comment.